Seal assemblies are used in a variety of applications where it is desired to maintain a pressure differential between an interior and an exterior of an object. The integrity of the seal assembly is critical to the maintenance of the desired pressure differential. In some applications, failure of the seal assembly can be catastrophic. Accordingly, it is desired to verify the integrity of the seal assembly.
Leak testing is one method used to verify the integrity of seal assemblies. Leak tests are performed by creating a pressure difference between two sides of a seal assembly and measuring the amount of fluid flowing from one side to the other. A common leak test employed to verify the integrity of seal assemblies is the hood test.
When performing a hood test, the object protected by the seal assembly is covered with a plastic hood (sometimes called bagging). The hood is pressurized with a fluid, such as helium gas. A detector is connected to the interior of the object, and any fluid leaking through the seal assembly is detected. Hood tests are often performed on seal assemblies mounted on vehicle access hatches such as, for example, space capsule hatches and submarine hatches.
For seal assemblies buried within the hatch, a conventional hood test can test the overall integrity of the seal assembly. However, some seal assemblies utilize redundant systems employing multiples seals. Because of a lack of accessibility for buried seal assemblies, a conventional hood test is limited to testing the overall integrity of the seal assembly and cannot test the integrity of each individual seal of the redundant seal system.